Lua Requires Chilkat v11.0.0+

Generate ECDSA Key and Get Details as XML

See more ECC Examples

Demonstrates how to generate an ECDSA key and gets the parts as XML. Lua

local chilkat = require("chilkat")

-- This requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

local ecc = chilkat.Ecc.new()

-- Generate a random ECC private key on the secp256k1 curve.
-- Chilkat also supports other curves, such as secp384r1, secp521r1, and secp256r1.

-- Create a Fortuna PRNG and seed it with system entropy.
-- This will be our source of random data for generating the ECC private key.
local fortuna = chilkat.Prng.new()
local entropy = fortuna:get_entropy(32, "base64")
local success = fortuna:add_entropy(entropy, "base64")

local privKey = chilkat.PrivateKey.new()
success = ecc:gen_key("secp256k1", fortuna, privKey)
if not success then
    print(ecc.last_error_text)
    return
end

-- An EC private key has this ASN.1
-- ECPrivateKey ::= SEQUENCE {
--     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
--     privateKey     OCTET STRING,
--     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
--     publicKey  [1] BIT STRING OPTIONAL (This is the ANSI X9.63 public key format.)

local asn = chilkat.Asn.new()
success = asn:load_encoded(privKey:get_pkcs1_enc("base64"), "base64")
if not success then
    print(asn.last_error_text)
    return
end

local xml = chilkat.Xml.new()
xml:load_xml(asn:asn_to_xml())

print(xml:get_xml())

-- The XML looks like this:
-- <?xml version="1.0" encoding="utf-8" ?>
-- <sequence>
--     <int>01</int>
--     <octets>JgJvBG+3wletkJab8iXAkpz0O8/AgWZSpkYVcB7SpnU=</octets>
--     <contextSpecific tag="0" constructed="1">
--         <oid>1.3.132.0.10</oid>
--     </contextSpecific>
-- </sequence>

-- The 32-byte private key is in the octets..
-- Get it as hex.
local crypt = chilkat.Crypt2.new()
local privKeyHex = crypt:re_encode(xml:get_child_content("octets"), "base64", "hex")

print("EC private key as hex = " .. privKeyHex)